In an elevating mechanism of the generic type known from U.S. Pat. No. 3,711,054 the cylindrical surface of the housing of the gas spring is directly guided in a guide bush connected with the guide tube. The gas spring is not only the supporting and longitudinally adjustable element but also the guiding and rotatable element of a chair or table column. Since the piston rod is secured in the bottom plate of the guide tube not only for free rotation but also with sufficient radial play, the gas spring can adjust to any possible and changing load directions of the seat or the table-top, whereby the risk of bracing within the guide bush is eliminated.
Longitudinally adjustable gas springs of the type used for this purpose are known from U.S. Pat. No. 3,656,593. These gas springs can have an additional protecting tube tightly connected with their housing, as it is known from U.S. Pat. No. 4,979,718.
In these known mechanisms the gas spring is the most expensive component in terms of construction and costs. Consequently, it is desirable that as many different chairs, tables or the like as possible be realized with types of gas springs that differ as little as possible. Constructive limits are set by the maximum travel defined by the above-described design.